Greetings 👋🏼 - my name is Marian 👩🏼💻 and I recently embarked on a journey to level up my SQL game by starting the 8 Week SQL Challenge by Danny Ma.
This repository contains all my documentation for the challenges that I have completed so far. Keep watching 👀 this space as I add on more solutions.
Solutions were coded in Google BigQuery syntax.
Each case-study folder contains the following files
- data.sql: compiled sql for creating tables & loading data (if no data.sql file, you'll find csv files instead)
- datacleaning.sql: compiled sql for cleaning data
- solution.sql: compiled sql for answering the challenge questions
My code was written in a Count SQL notebook.
From there I copied the compiled SQL to a *.sql file which you can view in the individual challenge folders.
I also copied the markdown from the notebook to a Craft doc to which I added some additional formatting together with the screenshots and/or csv downloads so you can see tabular output from the individual notebook cells.
Check the links below for all the documentationion for each individual challenge.
🔗 The Challenge
🔗 SQL Notebook
🔗 Markdown / Solution Comments
Lessons learnt
- The wonderous world of CTE's or Common Table Expressions
- Using WINDOW functions like DENSE_RANK
- Using STRING_AGG to concatenate non-null values
- Wrapped CASE statements (to filter, to aggregate)
🔗 The Challenge
🔗 SQL Notebook
🔗 Markdown / Solution Comments
Lessons Learnt
- Creating an array from a string using STRING_AGG
- Flattening arrays using UNNEST / CROSS JOIN
- EXTRACT returns an integer for the corresponding date part
- PARSE_DATE converts the string representation of a date to a date
- DATE_DIFF calculates the difference between 2 days expressed in specified datepart
- Using Window aggregations
- Wrapped CASE statements (to filter, to aggregate)
🔗 The Challenge
🔗 SQL Notebook
🔗 Markdown / Solution Comments
